Minerals separation process

ABSTRACT

Titanium oxide containing concentrates are recovered from sand composed in the particle size range of 100 mesh and smaller of titanium oxides, heavy metal silicates, and silica. A plural stage flotation process is used. In the first stage the sand in the above size range is subjected to flotation using air and an anionic collector to yield a heavy mineral concentrate. The second stage flotation involves treating this heavy mineral concentrate with nitrogen and an anionic collector to float off the heavy metal silicates, the titanium oxide concentrate remaining in the tailings.

United States Patent Sanders et [451 June 13,1972

[ MINERALS SEPARATION PROCESS FOREIGN PATENTS OR APPLICATIONS Inventors;Rom" N. Sander J I)I J h s 1 Canada l b th f Baton R La 120,465 10/1957U.S.S.R. ..209/ 167 73] Assignee: Ethyl Corporation, New York, N.Y.Prima'y Examiner Frank w Latter [22] Filed: Sept. 15, 1969 AssistantExaminer-Robert Halpet [21] APPL NOJ 858,124 Attorney-Donald L. Johnson[57] ABSTRACT [52] U.S. CI ..209/l66 [51] Int. Cl 3034 1 02 Titaniumoxide containing concentrates are recovered from 58 Field of Search..209/l66, 167 Sand composed in the Particle Size range of 100 mesh andsmaller of titanium oxides, heavy metal silicates, and silica. A pluralstage flotation process is used. in the first stage the sand [56]References Cited in the above size range is subjected to flotation usingair and an anionic collector to yield a heavy mineral concentrate. TheUNITED STATES PATENTS second stage flotation involves treating thisheavy mineral 2,525 l 46 lo 950 M cMurraym 209/166 X concentrate withnitrogen and an anionic collector to float off 2, 5 57.4 55 6/951 Moyer"209/166 the heavy metal silicates, the titanium oxide concentrate2,792,940 5/:957 Baarson ..209/l66 "mammg 'aflmiP 6 Claims, No DrawingsMINERALS SEPARATION PROCESS This invention relates to beneficiation ofheavy mineral sands and more particularly to the recovery. of titaniumoxide concentrates from sands whose heavy mineral contents are of smallparticle size 100 mesh or below).

Within the interior of the United States, particularly in areas alongthe Cretaceous coast lines there are potentially valuable heavy mineralplacer deposits. A feature of these sands is that the heavy minerals areof small particle sizei.e., most of the heavy minerals exist in the formof particles of 100 mesh size or smaller. In composition the smallparticle fractions of these sands are made up principally of titaniumoxides, heavy metal silicates, and of course silica or quartz. Thetitanium oxides usually involve mixtures of ilmenite, leucoxene andrutile. The heavy metal silicates present invariably include zircon andfrequently include monazite or staurolite or both. Other silicates suchas kyanite or sillimanite or both are also present in these smallparticle size fractions.

So far as is known no commercially feasible method for recovering atitanium oxide concentrate from sands of the foregoing character hasbeen reported in the art.

In accordance with this invention titanium oxide containing concentratesare efficiently and economically recovered from the small particle sizefractions of such sands by means of a plural stage flotation process.The first stage of the process involves subjecting the sand within thesize range of 100 mesh and smaller (e.g., within the range of 100/400mesh and preferably within the range of 100/200 mesh) to one or moreflotations using air and an anionic collector such as a carboxylic acidcollector to obtain a heavy mineral concentrate enriched in titaniumoxides and heavy metal silicates. In this first stage the tailings arecomposed predominantly of silica.

In the second stage of the process the heavy mineral concentrate fromthe first stage is subjected to one or more flotations using nitrogenand an anionic collector (e.g., a carboxylic acid collector) to floatoff heavy metal silicates and leave as tailings a concentrate enrichedin titanium oxides.

It will be seen that the process is a paragon of simplicity. The use ofexpensive chemicals and condition operations or the like is kept to aminimum. Moreover, titanium oxide containing concentrates of goodquality are readily recovered as the tailings from the second stageflotation(s).

With most sands of the type with which this invention is concerned it isdesirable to initially screen or otherwise classify the ore. As noted,the invention is particularly adapted for use with sands whose heavymineral content is concentrated within the fractions between 100 and 400mesh size. For example efficacious results have been achieved onsubjecting a 140/200 mesh size fraction of heavy mineral alluvial sandto the plural stage process.

In both of the flotation stages any suitable anionic collector may beused. For example use may be made of such common reagents as oleic acid,coconut oil fatty acid, talloel, saponified fatty acids, saponifiedtalloel, and others of a similar nature. Long chain monoandpolyunsaturated monocarboxylic acids similar to oleic acid and thecorresponding saturated fatty acids are generally suitable.

In the first stage it is particularly desirable to use a carboxylic acidcollector while keeping the pH of the aqueous pulp at from about 2.5 toabout 7. In most cases the best results are achieved when the pH of thepulp is in the range of from about 3.5 to about and accordingly thisrange is preferred. The inclusion within the pulp of a dispersing agentsuch as sodium fluoride has also been found advantageous.

The amount of the collector used will of course be governed to someextent by the character of the sand being treated, the flotationconditions being used, and the identity of the particular collectorselected for use. Generally speaking, however, the amount used in thefirst stage will range from about 0.1 to about 5 pounds per ton ofsolids treated. Amounts ranging from about 2 to about 4 pounds per tonare generally preferred.

For the second stage flotation operations the use of oleic acid as thecollector has been found to be of advantage especially when the aqueouspulp also includes sodium carbonate. However, other carboxylic acidcollectors may be used e.g., long chain monoor polyunsaturatedmonocarboxylic acids. As in the case of the first stage flotation(s) theamount of the collector employed will vary depending upon its identity,the make-up of the solids being processed, and the flotation conditionsbeing utilized. However, generally speaking the amount of the collectorfor the second stage will be in the range of from about 0.1 to about 5pounds per ton of solids treated. Good results are achieved when thesecond stage pulp has a pH of in the range of from: about 7 to about 11, preferably 8 to 10.

In the first stage air or air enriched with oxygen is used as the gasphase. On the other hand in the second stage use is made of eithernitrogen or air from which the oxygen has been largely if not entirelyremoved.

The pulp loadings in both stages of the process will vary from about 5to about 40 percent depending upon the properties of the solids beingprocessed. The flotations will normally be conducted at temperatureswithin the range of from about 20 to about 60 C., temperatures in therange of from about 30 to about 50 C. being generally preferred.Flotation times are generally up to about 5-10 minutes. The optimumflotation conditions for use with any given ore can readily beascertained by means of a few preliminary experimental trial runs.

The remaining conditions of the flotation steps are along conventionallines. For example common modifiers, frothers, dispersing agents (e.g.,sodium silicate), or like reagents may be used if desired.

In order to still further appreciate the practice and advantages of thisinvention reference should be had to the following illustrative example.

EXAMPLE A heavy mineral alluvial sand from Tennessee was used in theseoperations. Petrographic mounting showed that the sand containedilmenite, leucoxene, rutile, kyanite, zircon and quartz. Overall thesand contained titanium minerals in amount equivalent to about 7.4percent TiO iron minerals equivalent to about 1.9 percent of Fe, andaluminum minerals equivalent to about 5.6 percent A1 0 The balance waschiefly silica and zirconium species.

The sand was dried and screened. The relative amounts of each fractionand its analysis for aluminum, iron and titanium are given in Table I.

Using a Denver Equipment Company laboratory flotation machine, model D,multiple flotation runs were made on the /200 mesh fraction of Table I.In each of the nine runs the pulp had a pH of 3.5 and contained sodiumfluoride equivalent to 3.3 pounds per ton of sand and a commerciallyavailable tall oil fatty acid collector in amount equivalent to 2.5pounds per ton of sand. The flotations were conducted at 38 C. Thecollectives from these nine runs (12.7 percent of the 140/200 meshfraction) were combined, as were the tailings.

The combined collectives from the initial flotations were subjected to asecond series of flotations using the same reagents under the sameconditions with the exception that the tall oil fatty acid collector wasemployed in amount equivalent to 5 pounds per ton of collectiveconcentrate fed. In these flotations 60.7 percent of the total floatedwhile 39.3 percent did not float.

The flotation cell was then modified to use nitrogen gas rather than airand the total, combined collective concentrate from the second series offlotations was again floated but in this instance using sodium carbonateand oleic acid, each at the one pound per ton level. The pH of the pulpwas approximately 8. In this nitrogen-induced flotation operation, 48percent of the material floated, the tailings amounting to 52 percent.

The analyses for aluminum, iron and titanium on each of the abovecollective concentrates and corresponding tailings are presented inTable II.

TABLE II.

Partial Analysis of Flotation Concentrates, Wt.

1. A process for the recovery of a titanium oxide containing concentratefrom a sand composed in the particle size range of mesh and smaller oftitanium oxides, heavy metal silicates, and silica which comprises:

a. subjecting the sand within said size range to flotation at a pHoffrom about 2.5 to about 5 using air and a carboxylic acid collector toobtain a heavy mineral concentrate enriched in titanium oxides and heavymetal silicates;

b. subjecting the heavy mineral concentrate to flotation using nitrogenand an anionic collector to float off heavy metal silicates and leave astailings a concentrate enriched in titanium oxides; and

c. recovering said tailings.

2. The process of claim 1 wherein the sand is within the /200 meshrange.

3. The process of claim 1 wherein in Step (a) the collector is acarboxylic acid collector and the pH of the pulp is from about 3.5 toabout 5.

4. The process of claim 1 wherein in Step (b) the collector is acarboxylic acid collector and the pH of the pulp is from about 7 toabout 1 l.

5. The process of claim 1 wherein in Step (a) the collector is acarboxylic acid collector and the pH of the pulp is from about 2.5 toabout 5 and wherein in Step (b) the collector is a carboxylic acidcollector and the pH of the pulp is from about 7 to about 1 l.

6. The process of claim 1 wherein the sand is within the 140/200 meshsize range; wherein in Step (a) the collector is a tall oil fatty acidcollector, the pulp contains sodium fluoride dispersing agent, and thepH of the pulp is about 3.5; and wherein in Step (b) the collector isoleic acid, the pulp contains sodium carbonate and the pH of the pulp isabout 8.

PO-ww UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3, 6 9, 266 Dated June 13, 1972 Inventor(s) Robert N. Sanders and JamesD. Johnston It is certified that error appears in the above-identifiedpatent and that: said Letters Patent are hereby corrected as shownbelow:

Column I, line 21, I reads "a carboxylic acid collector", should read atall oil fatty acid collector Column 4 claim 3 should read as follows:

3.. The process of Claim 1 wherein in Step [a] carboxylic acid collectorand the pH of the pulp is from about 3 .5' to about 5.

Signed and sealed this" 27th day of February 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attestlng Officer I ICommissioner of Patents

2. The process of claim 1 wherein the sand is within the 140/200 meshrange.
 3. The process of claim 1 wherein in Step (a) the collector is acarboxylic acid collector and the pH of the pulp is from about 3.5 toabout
 5. 4. The process of claim 1 wherein in Step (b) the collector isa carboxylic acId collector and the pH of the pulp is from about 7 toabout
 11. 5. The process of claim 1 wherein in Step (a) the collector isa carboxylic acid collector and the pH of the pulp is from about 2.5 toabout 5 and wherein in Step (b) the collector is a carboxylic acidcollector and the pH of the pulp is from about 7 to about
 11. 6. Theprocess of claim 1 wherein the sand is within the 140/200 mesh sizerange; wherein in Step (a) the collector is a tall oil fatty acidcollector, the pulp contains sodium fluoride dispersing agent, and thepH of the pulp is about 3.5; and wherein in Step (b) the collector isoleic acid, the pulp contains sodium carbonate and the pH of the pulp isabout 8.